Data point: if you print out _handlerList immediately after the dictConfig() call, it *is* there, as I would have expected. The following script saved as logtest6.py:

from datetime import datetime
from time import sleep
import sys

if __name__ == '__main__':
    LOGGING = {
        'version': 1,
        'handlers': {
            'logfile': {
                'level': 'DEBUG',
                'class': 'logging.FileHandler',
                'filename': '/tmp/debug.log',
            },
        },
    }

    print('%s: starting' % (datetime.now(),))
    from logging.config import dictConfig
    dictConfig(LOGGING)
    from logging import _handlerList
   
    print('%s: after dictconfig' % (datetime.now(),))
    sys.stdout.flush()
    print('_handlerList 1:', _handlerList)
    # using importlib on a new file triggers the warnings
    import importlib, shutil, os
    print('_handlerList 2:', _handlerList)
    shutil.copy(__file__, __file__ + '.new')
    os.unlink(__file__)
    os.rename(__file__ + '.new', __file__)
    importlib.import_module('logtest6')
    sys.stderr.flush()

    print('%s: after error' % (datetime.now(),))
    sys.stdout.flush()

    sleep(5)
    print('%s: after sleep' % (datetime.now(),))

    # Vinay Sajip wrote:
    # > The handlers are AFAIK referenced - if you peek at
    # logging._handlerList or logging._handlers you should see them in
    # there.
    from logging import _handlerList, _handlers
    print('_handlerList 3:', _handlerList)
else:
    print('imported once')

When run, yields

$ python3.4 logtest6.py 
2015-01-06 12:26:46.910634: starting
2015-01-06 12:26:47.290223: after dictconfig
_handlerList 1: [<weakref at 0xb7223e34; to 'FileHandler' at 0xb71680dc>]
/home/vinay/projects/python/3.4/Lib/collections/__init__.py:373: ResourceWarning: unclosed file <_io.FileIO name='/tmp/debug.log' mode='ab'>
  exec(class_definition, namespace)
_handlerList 2: []
imported once
2015-01-06 12:26:47.388877: after error
2015-01-06 12:26:52.394514: after sleep
_handlerList 3: []